Support mat



FIG. 1 is a perspective view of my support mat in accordance with my invention;

FIG. 2 is a top view thereof;

FIG. 3 is a bottom view thereof; and,

FIG. 4 is a left side view thereof, the front, rear and right side views being the same.

The broken lines depict portions of the article that form no part of the claimed design. 

CLAIM The ornamental design for a support mat, as shown and described herein. 